This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. During every cell division, the genome must accurately replicate and segregate a complete set of chromosomes into each daughter cell. Failures in chromosome segregation have severe consequences for human health, since creating cells with an inappropriate chromosome number can lead to cell death, birth defects, or cancer. Our research focuses on condensins, conserved proteins that ensure accurate chromosome segregation by organizing chromosome structure during meiosis and mitosis. Condensins bind chromosomes and are thought to use the energy of ATP hydrolysis to wind DNA into large loops. We showed that C. elegans has two condensin complexes with overlapping components and distinct functions in mitosis and gene regulation. Our previous work also suggested that condensin functions beyond simple compaction to promote sister chromatid resolution and centromere organization. To learn more about condensins, we are now taking a functional proteomics approach to identify condensin-interacting proteins. Preliminary results have identified new condensin subunits, unexpected subunit interactions, and regulatory proteins that point to mechanisms for tying condensin function to the cell cycle.